A hydraulic shock absorber that absorbs road surface vibration input into a vehicle includes a damping valve that damps vibration by applying resistance to a flow of working fluid. JP01-111840U, published by the Japan Patent Office in 1996, proposes a damping valve structure for reducing an effect of a viscosity of the working fluid on a generated damping force.
The damping valve includes a main leaf valve seated on a valve seat and a sub-leaf valve seated on a hole portion formed in the main leaf valve. By setting a valve opening pressure of the sub-leaf valve to be lower than a valve opening pressure of the main leaf valve, working oil flows through the sub-leaf valve when a shock absorber strokes at a low speed, and when the shock absorber strokes at a high speed, the main leaf valve opens.
By constructing the damping valve in this manner, the effect of the viscosity of the working fluid on a damping force characteristic of the damping valve can be reduced even when the viscosity of the working fluid is high, for example at a low temperature or the like.